Ejectable seat for aircraft



Nov. 2, 1954 M. J. o. LOBELLE EJECTABLE SEAT FOR AIRCRAFT 5 Sheet s-Sheet 1 Filed June 2, 1952 Nov. 1954 M. J. o. LOBELLE EJECTABLE SEAT FOR AIRCRAFT 5 Sheets-Sheet 2 Filed June 2, 1952 By W %tiomeys 1954 M. J. o. LOBELLE 2,693,326

EJECTABLE SEAT FOR AIRCRAFT Filed June 2, 1952 5 Sheets-Sheet 3 Inventor fima l/uza 50/107 [05245 Nov. 2, 1954 J. o. LOBELLE 2,593,326

EJECTABLE SEAT F OR AIRCRAFT Filed June 2, 1952 5 Sheets-Sheet 4 United States Patent 2,693,326 EJECTABLE SEAT roR AIRCRAFT Marcel Jules Odilon Lobelle, slough England, assignor to M. L. Aviation Company Limited, Slough, England,

a British company Application June 2, 1952, Serial No. 291,113 Claims priority, application Great Britain June 4, 1951 7 Claims. (Cl. 244-122) This invention relates to ejection apparatus for aircraft in which, in the case'of an emergency, a seat can be propelled by an expulsion device along guides and ejected through an opening in the aircraft, thus enabling the airman to make a safe descent by parachute.

The airman is generally strapped to his seat by means of releasable attachments between his combined parachute and safety harness and the seat. These attachments can be automatically released when the airman is ejected in an emergency in the air, but on the ground they must be operated by hand. Moreover there are other operations which have to be carried out, such as removing a cockpit canopy before'the airman is free to climb out of the aircraft. It may happen, therefore, that in the eventof a crash or forced landing, particularly when fire breaks out, craft lands in water, the airman may not have an opportunity to make his escape due either to injury or to other reasons. p 7

According to the present invention, in the event of a crash landing, -a cover in the roof of the aircraft is automatically opened and the airman is ejected at a relatively low velocity which is just sufficient to throw him clear of the aircraft. If the aircraft has landed in Water, then the automatic operation may be initiated by one or more immersion switches which serve to complete the necessary operating circuit. On the other hand, if the landing is on land, the operating circuit may be arranged to be completed by one or more inertia switches operated by the shock of landing and these may, of course, be connected in parallel with the immersion switches so that the ejection apparatus is brought into action for any type of forced landing. I

Whether the landing is on water or land, it is obviously undesirable for the airman to be ejected if the aircraft is inverted, and for this purpose a gravity-operated switch, which is opened if the aircraft is inverted, may also be included in the operating circuit. If the apparatus is to be used in a pilots cabin where a retractable gunsight is used, this must first be retracted in order to allow for the ejection of the pilot. The retraction may be initiated, therefore, when the cover in the roof of the aircraft is opened and the completion of the retraction may then serve to bring about the ejection of the pilot. 1 I

The normal type of cartridge for ejection in the air is very much too powerful for the low velocity ejection required, and an alternative source of power must be employed. An ejection gun having two separate breeches may, therefore, be used, of which the main breech is used in conjunction with the normal cartridge for producing high velocity ejection during'fiight and an auxiliary breech is used for obtaining the low velocity ejection. For this low velocity, although other forms of power such as compressed air may be used, it is preferred to use a small explosive cartridge situated in communication with the auxiliary breech and to provide the necessary valves for the selective connection of the two breeches with the ejection cylinders of the gun.

Apparatus in accordance with the invention-will now be described in more detail by way of example with reference to the accompanying drawings, in which:

Figures 1, 2 and 3 show the sequence of operations when a pilot is ejected after landing in water;

Figure 4 is a circuit diagram of the electrical controlling apparatus;

Figure 5 is an elevation of the ejection gun viewed from one side;

or alternatively, if the airi switch illustrated. At the same 2,693,326 Patented Nov. 2, 1954 Figure 6 is a partial sectional viewed from the other side, and

Figure 7 is a side as Figure 6.

Figure 1 shows the pilot in position in the cockpit of his aircraft before making a forced landing. The pilot is strapped to his seat 1, which is'arranged to slide in guides 2. The cockpit is enclosed by a canopy 3 which closes an opening 3a in the top of the roof 3b of the cockpit and a gunsight 4 obstructs upward movement of the pilot. An immersion switch is indicated diagrammatically at 5 and may be one of a number of such switches distributed around the aircraft. This switch is a pair of spaced electrodes, as shown in Fig. 4, between which a circuit is completed in the presence of water. As shown in Figure 2, the aircraft has landed in water and ice ' the immersion switch 5 has become flooded. As a first step, the canopy 3 has been jettisoned in any suitable manner and the gunsight 4 is in the process of being retracted. For this purpose a small electric motor, 6 is provided driving a lead screw 7 which withdraws the gunsight 4 down guides 8. As soon as the gunsight is fully withdrawn, the pilot, complete with his seat 1 is ejected as shown in Figure 3. The velocity. of ejection is relatively low and is suflicient merely to throw the pilot clear from the aircraft so as to enable him to rise to the surface of the water.

This sequence of operations is controlled by the circuit shown in Figure 4. The circuit passes from the positive supply line 11 through a fuse 12 to a manually operated double pole changeover switch 13. In the safe position of the switch as shown in the drawing, the lefthand pole is connected to a pair of warninglights 14 and thence to a pair of immersion switches 5 connected in series. It is necessary to connect two such switches in series to guard against accidental operation of the circnit which might be caused by deterioration of the chemical filling of the switches. By connecting two such switches in series the possibilities of both deteriorating are reduced to negligible proportions. Thus the switches connected together in pairs are fitted in various parts of the aircraft and the pairs are connected in parallel with For simplicity only one such pair of one another. switches is shown.

' The further side of the pair of immersion switches is thus connected via the right-hand pole of the switch to the negative of the supply, which is earthed. If by any chance both of the immersion switches have become conductive, then in the safe position, a circuit will beestablished through the warning lights, and the pilot will be warned of this condition before take-ofi. Provided, however, that the lights do not light up, the switch may be changed to the alternative or operative position in which the left-hand pole completes a circuit through a gravity-operated switch 15 and then alternatively through a pair of immersion switches 5 and an insertia switch 16 connected in parallel with the immersion switches. 'As shown the gravity switch consists of a glass tube 15a partly filled with mercury 1512, which makes contact between electrodes 15c and 15d when in the upright position. When in the inverted position, the mercury fiows to the other end of the tube to interrupt the circuit; The tube is formed with a neck 15e in the manner of an hour glass to prevent spattering of mercury when the switch.

is inverted. Any suitable form of gravity-operated switch may, however, be included in the place of the mercury completed via the right-hand pole of the switch through the warning lights which are, therefore, illuminated continuously to indicate that the switch is in its operative position. f

Under normal conditions, neither the -iinmersion switches nor the inertia switches are conductive so that the circuit is interrupted at this point. In the event of a crash landing, however, either the immersion switches become conductive owing to the presence of water or the inertia switch is rendered conductive by the shock of landing and the circuit is then completed through a cartridge fuse 17 to earth at 18. The cartridge fired by this fuse 17 starts the retraction of the gunsight which is accomplished v in the manner shown in Patent No. 2,569,818,

elevation of the gun.

partial outside elevation from the same time, a circuit is also' 1 The.completiomofithis...retraction-causesaminterlockcartridgefuselS. .to. the. negative, -supply.'24 and thus .fi'res a-,small'1cart'ridge...in the. ejection; gun to. eject the pilot asi shownin :Eigure. 3'1.

Theejectiorrzgunifselffjis. shownindetail in Figures 5...? to 7. Tliegunincludsa mairlbody 30'connectedlhyi trunnibns .31j.to,.the frame. of the; aircraft at .32. It is frmedwithia mainlb'reech3lfor the reception of a cartridge givifig ..high. velocity ejection under airborne con-r ditionsin the-manner. shown .in .PatentNo. 2,579,683 and witlipaniauxiliary. breech.34.for.the reception of'a..con-. siderab'ljq. smaller. cartridge for, ejection, under. crash land ingpOnditiOnsn Tl'i'erauxiliaryb'reech 34 is provid'edfwith' an. exhaust port 2S.-'1eadi'ng, to theatmosphereso that ,if flier-cartridge 'i's';inadvertently.. fired,.the force of the exposionris. expendedlwithoutv damage. A port 40.1eading fr'omthe auxiliary; breech. to. the ejection orexpansion. cylinders. ofwthegun indicated in dotted'. lines at, 36 is. normally closed by a flap, valve 37' turning on a spindle 3.8. This-flap valve.consists ofapair. of,p lates,37a' and 3.7bfmountedlon either side of aball headed arm 39 which. giyesllievalve .a-=,certain amount of free motionallowing; if..,to.,se-at, squarely either. atthermouthofthe port.35 or ofthe port 40.

Thercartridgezin the auxiliary. breech 3.4 'is fired electrieallyl .by;means.of$the.fuse 23 as already described, and immediatelyprior. to..its..fi'ring, the flap valve 37 is moved bjqmeansiof 'thesolenoid'20 into the position in whichv itscovers the. exhaust port 35. The operation of the so1enoid120i(as.seenin,.Figure moves the-tip of the armature. 50".clear .of one arm 51 ofa bellcrank .lever .52 secured to the spindle 38 on which the flap valve 37 'is mountedi. The. second'arm.53 of the bellcrank lever is actedrj'on byaspring S Lguided'by a rod 55; and when thearmaturer50is moved clear. of the tip of the arm.51, thexspringz54'forcesihe arm 53 downwardly, causing the spindle 38to rotate in" a counter-clockwise direction as seen-in'Fi'gureSE AsseeninFigure -6, this gives the flap valve-37, a'clockwise-movement; serving to close the exliaustportr35 and"toopen the port 40to' allow the expo'sive force-"fromthe'cartridgein the" breech 34 to pass into the.ejection cylinder of the gun and'thus' eject/the airmam-- The-main'breech33-contains a considerably larger. cartridge; which-is-firedimechanically bythe pliot under airborne-.z'conditionsr Thisbreechis also provided with an exhaust port 60, which" normally connects directly with .th'e breeeh but which may be closedby aflap valve: 61=turning about a" spindle 62; The. valve 61 has a sirni-' larconstruction' to zthe'valve37 and in its alternative position-seals-the-exhaustport andallows the explosive" force ffomz-the main b'reeeh -33-'to pass into the: ejection cylinders-.36 of thegun:

main 'b'reeeh; ora'lternatively, the explosive fOI'C6"f1'OInf thes main b'reech blowing' ba'ck into the auxiliary breech; a tftirther flap valve =63 i is providdh'avinga similar con structionutorthe valves-37 and 61 and turning-about'a spindle 64i In. the position shown" in Figure 6; the-valve-63 is seated against themouth of a port 65 leading-fromthee'main- -breech- 33 -to-the=ejection=cylinder 36. Thus flie -explosive force from the auxiliary-breech merely serves-11o force'the valve.631more firmly against its seating and sopositivelyseals' the port 65. Similarly, in its alternativet'position, the-valve 63 seats firmly against theamouthvlofihetport40, against which it is pressed more'firmlyaby the explosive=force from themain breech.

Both the valves 61 and 63 must be moved from the positiomshown in Figure 6 to their alternative positions immediately beforethe cartridge in the main breech slot 74" co-operating .with; arpin 75-, mountedat the. end;

of a short lever arm 76 fixed to the spindle 62 of the Inorder to prevent" the: exposive force-from the -auxiliary breech. blowing back. intothe' valve. 61.- Operation. o.t .the connectingmd 70.. rocks the plate 72 in a clockwise direction and the first part of the movement serves tozfree a nose portion 77 on the plate 72 from a corresponding latch 78 formed on a sliding bar 79 connected to-the firing mechanism of the breech 33. During this initial part of the movement, a curvedqpprtiom-SQ. ofathezcam: slot 74'moyes around the pin 75 and gives it no appreciable movement. The pin:.75,' howeventhem entersanportion' 81 off' the cam slot; .rwh ichvmoves titwupwardlyvand to' therightas :shown in Figure 5, rocking the spindle 62 irra -cloclewisedirection so. as to.move,the valve .61 to closethemouth of the exhaust port-*60- and'to*operr themouth-of the port 65. As the plate. 72 approaches the..limit. of. its. travel, a cam surface 82; formedas a bulge on the plate 72, engages a roller:83,mounted;1on;.thebottom of the bar 79, sliding this upwardly to operate the firing mechanism and so. fire .the cartridge. in .therbreech.

At. the same..time, .the. turning, motion. of fthe/plate. v72. has also servedto turn.the sp indle(73. ina clockwise, direction...as.. seen in Figure; 5 ,1 and. in. an. anticlockwise. di. rection as seen1.,ir'r Figurefll'. ontheendlofthe spindle. 73 remote from..the..plate..72iis connected an arrn.85.1p rovided. at: its endwith a.v rotatable. b'ush'f. 8'6 "formedwith. a. transverse bore. throughrwh'ich. passes. a,.rod. 847 10 theendrof whichja nut .88.,is secured. The..counter.-clock.-. wise movement oflthearm. 85'p,resses..against a washer. 88a sliding. on..the rod 8.7 and rcompressess a spring -.89,' soastomove therod 8.Tto thexrigh't'...

The ri'ght-handlend. of," the. rod.' is..p ivoted at. 90-to a. toggle linkage consisting of f. a .lever.-. arm .91 connected. to the. spindle: 64 carrying thervalve. 63, anda rod 9.2., whichis slidablethroughqa rotary bushing;93, mounted in a bracket: 94 ;secur,ed1to ,th'e .body, of the:g unE30.'-. A spring 95.,acting between {the bushing-:93 and an enlarged head 96'of'the rod92 serves to resist this sliding-mover. ment.. Thenactioru of. the-two..- springs: 89 and 95. isz to resist. the..counter-clockwise movement of the arm.- 85, and .as the..lever 9.1 .is-.:r.ocked in .a ,counter-clockwisedi: rection the; dead-centre position -..of.. the. toggle. is=reached and; under the, action; 0f..the; two-.-spring s,,,it,-rapidly. snaps: over; into :the. position shownv .in ,dotted; lines;- This givesan. abrupt. counter-clockwise; motion of. the; spindle 64- asseeninFigures; 6 and..;7,.moving;. thenvalve- 63; with: a.-. snap, action; from. engagementswith. the mouthiofith'e port. 65; to, engagement. with t the mouthroft the filial-D14 4 where. it. is.r held by; the; pressure -of .the,- springs 89.=-an.d, v95.-v Thisaction occurs-:during the movement o.-the;plate. 72.- and immediately prior: to.-the,sfiring ofnthercartridgez in the breech 33. Thusiby-theetime-ther cartridgefiiit-is; fired, ,the valve 6.1 has moved .to -blocldtheaexhaustiport 60=and :the .valve: 64v hasimoyed: to. open ather-pont 65; and: close the. pprt 40 -,solthattthe force. of thQfEXPiOSiOHiPfl-SSES: directly into; the. ejection cylinders v36, to. provide: the: necessary: ejective -for.ce=-.

Il'mWlil be. understood thatsonceihe-sequence .of roperaat1ons..has-beenlinitiatedJeithen by On61fOfith3iHImfSiDE sw1tchesor by theainertia; switchnitzproceeds'; :cornpletelp automat cally and-the: airman .is; safely ejected evenvift UIICQIJSQIOUS'. Asyalready mentioned;.a numbert'ofz ima- 111ES101JLSWIICh6S connectedlin pairs inzseries zrnawbez disetrlbuted over the aircraft, so that they-will; comesintor action whatever. part of; the: aircraft is; immersed. 'Ir'nmersion. switches suitable; forstheepnrposeiareawell known: and any,ofganvarretyiofrkinds rmayshe used-b. .Moreover; a .numberof inertia-; switchesnmayrhezi used, connected in parallel andlarrangedrso thattone or; morezwilll opera ate whatever.-the. .direetio1r. offthezinertia shockproduced bythecrash landing. Again, .suchsswitchesrare :well known anduany, one.-of-. a var1ety,-of-:types;-.may:be: used' for-the purpose.

I. claim:

1.. In: an. aircraft. having a roof: with;;an opening; ejec: tion apparatus, comprisingrinscombination; mseatafon anau'man, guide means: mounting: said seat: forsliding motion towardsisaldt Openingin-;;tl1'e.;-roof:of said aircraft; means for, e ecting saidg seats: through;-. said opening at a. ICIMIYBIX- low velocity sufficient :to::throwzcsaid' seat clear of said: aircraft anielectriercircnit'.controlling said e ection .means and .an1elcetrie-switch imsaid ,circuit; said sw 1tch b61l1g leSPO11S1.V; to: crash landing: conditions: of" saidaircrattito closezthe circuit; J

2. E ectlon apparatus as claimed in claimil; inrwhiclr sa1d-.sw1tcl1;t raresponsive to. 1m in ersiomin water:-

3. E ection apparatus as claimed in claii'n l, in which' sa1d switch is responsive to inertia shock.

4. In an aircraft having a roof with an opening, ejection apparatus comprising in combination, a seat for an airman, guide means mounting said seat for sliding motion towards said opening in the roof of said aircraft, means for ejecting said seat through said opening at a relatively low velocity, and electric circuit means controlling said ejection means, said electric circuit means including an immersion switch and an inertia switch connected in parallel, and a gravity-operated switch connected in series with said immersion switch and said inertia switch, whereby said circuit means is interrupted when said aircraft is inverted.

5. In an aircraft having a roof with an opening, ejection apparatus comprising in combination, a seat for an airman, guide means mounting said seat for sliding motion towards said opening in the roof of said aircraft, a guusight mounted in said aircraft and normally interrupting the passage of an airman when said seat is ejected, means for retracting said gunsight, an

ejection gun for ejecting said seat through said opening at a relatively low velocity, means responsive to crash landing conditions for initiating operation of said gunsight retracting means, and means responsive to the completion of the retraction of said gunsight for operating said ejection gun.

6. In an aircraft having a roof with an opening, ejection apparatus comprising in combination, a seat for an airman, guide means mounting said seat for sliding motion towards said opening in the roof of said aircraft, an ejection gun for ejecting said seat through said opening at a relatively low velocity, said gun comprising a main breech, an auxiliary breech, an expansion cylinder, valve means selectively connecting said main breech and said auxiliary breech to said expansion cylinder, means enclosing an explosive cartridge in said auxiliary breech and means responsive to crash landing conditions of said aircraft for operating said valve means for connecting said auxiliary breech to said expansion cylinder and for detonating said cartridge.

7. In an ejection apparatus for aircraft, an ejection gun comprising in combination, an ejection cylinder, a

main breech formed with a port communicating with said ejection cylinder, an auxiliary breech formed with a port communicating with said ejection cylinder, means for enclosing a cartridge in said main breech, means for firing said cartridge in said main breech, means for enclosing a relatively small cartridge in said auxiliary breech, means for firing said cartridge in said auxiliary breech, means forming an exhaust port for said main breech, means forming an exhaust port for said auxiliary breech, first valve means alternatively closing said exhaust port of said main breech and said port leading from said main breech to said ejection cylinder, second valve means alternatively closing said exhaust port of said auxiliary breech and said port leading from said auxiliary breech to said ejection cylinder, third valve means alternatively closing said port leading from said main breech to said ejection cylinder and said port leading from said auxiliary breech to said ejection cylinder, means for simultaneously operating said first and third valve means to close said exhaust port of said main breech and to open said port leading from said main breech to said ejection cylinder, and means for operating said second valve means.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,956,494 Dagnall et a1 Apr. 24, 1934 2,160,974 Lueck June 6, 1939 2,470,783 Mead May 24, 1949 2,499,993 Gregg Mar. 7, 1950 2,527,020 Martin Oct. 24, 1950 2,569,638 Martin Oct. 2, 1951 2,579,683 Lobelle Dec. 25, 1951 FOREIGN PATENTS Number Country Date 179,936 Switzerland Mar. 2, 1936 

